Since tattoos are associated with criminality in Japan, tattoos is strictly forbidden and cannot be shown on teachers in Japan. It’s a part of western modernity where tattoos are encouraged and considered beautiful, the Japanese rejects.
This used to be the case in the west too, not so long ago. That tattoos have become mainstream suggests to me that many westerners subconsciously identify with or want to emulate certain traits of criminal/antisocial elements (antisocial="alpha" in western countries). It's a faux-bravado/one-upmanship for men, a celebration of slut-hood for women.
Of course no tattoos in schools is a good sign, since schools should be instilling good values and demanding certain standards of prosocial behavior. Are you finding this to be the case in other aspects of Japanese schools and culture in general? Do you find it less degenerate than the west?